There are many types of fluid-tight slide fasteners wherein a stringer tape supports along one side of each edge a row of continuous coupling elements and on the opposing side a sealing member, thereby creating a waterproof or fluid tight fastening mechanism.
When the fastening or coupling elements are comprised of a continuous coil, the coupling elements are most commonly woven or knitted onto the stringer tape or alternatively are stitched to the tape surface at the edge of the tape.
There is a constant need for slide fasteners which are waterproof and fluid-tight and which can meet the demanding requirements of the modern world where extreme sports activities are ever more accessible to adults and children alike.
When applied to outdoor pursuits garments it is necessary for the slide fastener to be strong, hard wearing and most importantly substantially impervious to fluids. However, the waterproof covering applied to the external surface of the stringer tape is often a weak point in terms of fluid access be it in the form for example of snow, ice, or water-spray.
Prior art teachings have sought to solve this problem and the following slide fasteners have been disclosed.
In U.S. Pat. No. 6,343,408 B1 (YKK Corporation) there is described a pair of fluid-tight slide fastener carrying tapes upon which are located rows of coupling members and which are overlaid by a soft, synthetic rubber or similar covering layer.
The pair of continuous rows of coupling members are sewn to the carrying tapes in a spaced offset position transversely to the longitudinal edges of the carrying tapes such that the press-contact edge portions of the soft covering layers are in contact with one another along a longitudinal plane which intersects the slide fastener at a central axis thereof and which runs at right angles to the slide fastener plane.
The press-contact edge portions of the covering layer project over the longitudinal plane when the coupling member rows are disengaged. However, when the coupling member rows are engaged the edge portions of the covering layer are bent away from the tapes carrying the coupling member rows and are caused to extend roughly at right angles to the slide fastener.
The press-contact edges of the soft covering layers therefore engage one another under pressure when the slide fastener is closed creating a fluid-tight slide fastener, and thereby preventing fluid from passing between the press-contact edges of the soft covering layer.
Unfortunately, a problem exists with this type of slide fastener arrangement in that when the two press-contact edges or sealing lips of the covering layer are brought together it is quite easy to disturb the press-contact edges thereby breaking the fluid tight seal.
The seal may also be readily disturbed or damaged for example in the manufacturing process by bending or creasing the covering layer thereby mis-shaping the sealing zips and the contact edges.
Furthermore, as grease is an essential component in the manufacturing process of such slide fasteners, the application of grease to the covering layer may also result in a ready distortion of the sealing lips or contact edges as the lips are caused to slide over one another. This again leads to a fracture in the abutment of the sealing lips with the resultant ingress of water as one of the lips may slip out of position with respect to the opposing lip. As the use of grease to ease the motion of slide fasteners especially ‘heavy duty’ slide fasteners is a quite common practice, the misalignment of the sealing lips is a significant issue when preparing fluid tight slide fasteners, an issue which the present application seeks to address.
In U.S. Pat. No. 3,668,745 (Krupp) there is also disclosed a sealing closure or slide fastener having sealing lips for providing a fluid-tight seal over interlocking teeth or coupling elements. In this document the coupling elements do not project beyond the edges of the stringers carrying them in the closed position. Instead, relatively small sealing lips are provided close to the neutral axis of the coupling elements and when the coupling elements are closed the edges of the stringers are turned over bringing together the sealing lips of resilient material and thereby creating a fluid tight seal.
This type of arrangement whilst providing a suitable fluid-tight fastening mechanism is complicated in design and hence much more expensive to manufacture. It also requires a specifically designed shape of coupling element which renders standardized production of the slide fastener more difficult and expensive, especially for larger and more ‘heavy-duty’ slide fasteners with more rigid tapes.
In U.S. Pat. No. 2,923,992 (Armstrong) there is again described a flexible slide fastener capable of providing a suitable seal against the passing of water, air and other fluids. In the slide fastener described herein there is provided a pair of textile stringers with fastener teeth mounted in series on adjacent edges of said stringers and an impervious layer of material mounted on one side of the stringers.
However, in U.S. Pat. No. 2,923,992 the abutting edges of the impervious layer of material are angled differently with respect to each other such that when the slide fastener is closed the abutting surfaces or sealing lips are at an acute angle with respect to the closed plane of the coupling elements thereby creating an angled abutment. This has the potential for an uneven abutment between the sealing lips and hence an uneven closure mechanism leading to a non-planar arrangement of the sealing lips.
In U.S. Pat. No. 4,580,321 (Yoshida Kogyo K. K.) there is described a fluid-tight slide fastener comprised of a pair of slide fastener stringers joinable along their respective longitudinal edges, with support tape and a row of continuous coupling elements extending longitudinally on the side of the tape. An elastomeric sealing member overlies one side of the tape and has a longitudinal contact edge portion transversely projecting beyond a median plane of symmetry defined by said slide fastener halves in engagement, said plane being perpendicular to a general plane of said elastomeric sealing member.
In U.S. Pat. No. 4,580,321 however, the sealing members on each side of the slide fastener create an uneven and unattractive ridge when the slide fastener is closed and furthermore, due to the blunt nature of the elastomeric sealing member on each side of the tape, the final shape of the sealing member when closed can not be controlled. This can therefore lead to the inherent problems of slippage of the respective sealing members on each side of the tape with the resulting potential ingress of fluid.
In U.S. Pat. No. 3,501,816 (Heimberger) there is disclosed a fluid-tight slide fastener comprising a pair of inter-engageable elastomeric sealing strips wherein the elastomeric material encapsulates the coupling elements on each side of the respective stringer tapes. The slide fastener halves are originally laterally reversed with respect to one another and are interconnected for extrusion of the elastomeric material therearound.
Also disclosed are slide fasteners in which a prominent and strongly projecting tip or rib of elastomeric material is disposed on each side of the stringer tapes. The lips or ribs of elastomeric material extend someway beyond the edge of the coupling elements when the slide fastener is in an open arrangement. Whilst the relatively soft elastomeric lips or ribs do not affect the slider operation on the slide fastener, the abutment of the lips or ribs can not be controlled leading to an uneven abutment with the resultant ingress of fluids.
In U.S. Pat. No. 4,888,859 (Yoshida Kogyo K. K.) there is again described a water-tight slide fastener which comprises a pair of support tapes each coated on one surface with a water resistant material and including a row of coupling elements mounted on each of the tapes along the longitudinal edge.
The spaces or gaps defined by the interdigitation of the rows of coupling elements are completely filled by a filling core which swells when in contact with a liquid and thereby prevents entry of the liquid into a garment to which the fastener is applied.
The filling core is formed from a polymeric fibrous material which is highly water absorptive and capable of swelling upon wetting with water, and which is further highly water retentive against pressure in normal use.
In addition, in one embodiment of U.S. Pat. No. 4,888,859, the slide fastener is concealed and the tapes are coated with a watertight layer on one of the surfaces and include a folded edge portion further comprising waterproof strands which abut at the edges of the opposed tapes.
There is no mention in U.S. Pat. No. 4,888,859 of a coupling mechanism in which the waterproof layer is shaped to specifically ensure that when the edges of the waterproof layer abut there is no slippage and no misalignment of the edges of the sealing lips of the waterproof layer. The ingress of water into the slide fastener in U.S. Pat. No. 4,888,859 is prevented by the presence of waterproof strands which block any gap arising between the tape edges and the watertight layer.
Finally, in U.S. Pat. No. 6,427,294 B1 (YKK Corporation) there is described a waterproof slide fastener wherein a laminated synthetic resin film comprised of a low melting point resin layer and a high melting point resin layer, is fused to an entire surface of at least one face of a fastening tape in the slide fastener such that the lower melting point resin layer is in contact with and opposes the surface of the fastener tape while fastening elements are mounted on a side edge of the fastening tape.
Therefore, the ingress of water is prevented in U.S. Pat. No. 6,427,294 B1 by a multiple layer of resins which in combination provide a waterproof layer. Also in U.S. Pat. No. 6,427,294 the waterproof layer extends around the edges of the tape, and yarns are used which are fused into position to prevent any ingress of water.
There is no mention in U.S. Pat. No. 6,427,294 of a waterproof layer which comprise fins and which is shaped so that it does not extend past the edge of the coupling elements when the fastener is in the open position and which abut to form a substantially planar waterproof layer such that the sealing lips do not move with respect to one another and allow the ingress of water.